Lumber
Wood is a wood product of at least 6 mm thickness, by sawing of round timber is made parallel to the stem axis. It can be sharp-edged or have tree edges .
The freshly cut wood (as a standardized product according to DIN 68252 terms for sawn timber, shape and dimensions ) does not yet have a building authority approval for use as construction timber (as structural timber ) for load-bearing or reinforcing purposes. To do this, it must first have a wood moisture content of max. 20% dried (to be able to assess curvature and shrinkage cracks) and then sorted according to the load-bearing capacity based on the criteria specified in DIN 4074. Some of these sorting criteria are e.g. B. the position and size of branches, the type, position and depth of cracks, as well as the fiber inclination (the wood fibers should run as parallel as possible to the longitudinal axis of the wood cross-section). Only wood that meets the grading criteria may be used for load-bearing or stiffening purposes in construction .
Formats
Depending on the use, the products can be based on different standards with different dimension definitions:
| DIN 68252 | DIN 4074 (for construction timber ) | typical or traditional dimensions | ||||
|---|---|---|---|---|---|---|
| Art | Thickness d | Width b | Thickness d | Width b | Thickness d | Width b |
| bar | ≳ 200 mm | |||||
| Squared timber | ≥ 60 mm | ≤ 3 * d | ≥ 40 mm | ≤ 3 * d | ||
| Bohle | ≥ 40 mm | ≥ 2 * d | ≥ 40 mm | ≥ 3 * d | ||
| Hall * | 30-50 mm | ≥ 2 * d or ≳ 80 mm | ||||
| board | 8 mm ≤ d ≤ 40 mm | > 80 mm | ≤ 40 mm | ≥ 80 mm | ||
| bar | (A ≤ 32 cm²) | ≤ 80 mm | ≤ 40 mm | <80 mm | 18-40 mm | 48-60 mm |
| strip | 3 .. <16 mm | <80 mm | ||||
| veneer | <3 mm | ≥ 80 mm | ||||
| Sawn veneer | 1.5-10 mm | ≥ 80 mm | ||||
| Veneer strips | <3 mm | <80 mm | ||||
Cuts
The right side is the side of a board facing the middle (the core ) of the original trunk. On the right side the annual rings are closer together. It becomes convex when it dries . The left side is the side originally facing the bark of the trunk. It deforms into a concave shape when it dries . The annual rings are further apart. Some annual rings can have a broad flake .
Delinquent, full-edged and swaged
- full-edged
- is called sawn timber that has clean cut edges
- lagging or tree-edged
- is called sawn timber that still shows parts of the curve, one speaks of forest fringe or forest edge
- swerved
- is called the trunk after an outer fillet has been removed from part of the circumference. The discarded section is called the rind , it is quite worthless.
In addition, when a distinction is heartwood yet fully edgy sapwood - here the edge is also free from the inferior, external splint .
Types of cuts
- All wood
- The full cross-section is used, full-edged or tree-edged, also without sapwood. Whole wood is almost square up to the cross-section of the greatest load-bearing capacity as a horizontal beam without a lateral guide (1: √2 ≈ 1: 1.4). It is mainly used for beams or strong squared timber. With a single-stem cut , the round timber only has a single beam. Planks, boards and strips cut from the remaining cross-section are called sideboards .
- Half wood
- The log is core separated into two parts. For beams, planks and other squared timber, the usual format is between 5: 7 and 5:10 (1: 2). Previously popular in carpentry because it represents a good compromise between stability, peace and price, today it is often replaced by laminated beams .
- Cross or quarter wood
- Quarter - we only speak of cross timber if the sawn timber produced in this way has a cross-sectional area of more than 32 cm² (i.e. thicker than a wooden lath)
- frame
- at least 6 pieces made from a round log, also thicker than a lath.
The first three types of cut are summarized in the carpentry trade as bandage wood , finer subdivisions as cut goods .
- Middle wood, heartwood, heart boards
- Middle boards are cut from the middle of the trunk and have largely standing annual rings, provided the core of the tree is cut out. The middle board is also known as the heart board . In order to limit the bulging when drying, middle boards are usually cut open and reassembled.
- Sideboards, rinds
- All boards further out are called side boards . Rinds have only one continuous straight surface. The back of the rinds are not trimmed, i.e. H. they consist of the raw outer surface of the original trunk.
Types of incisions
- Single cut, sharp cut, board cut, plank cut or gate cut
- Cutting the trunk into a number of boards or planks, either directly framed and then individually hemmed (results in the higher yield) or the tree glued on both sides and then cut into boards of the same width (today the usual, faster way).
- Flat cut, cantibay cut
- First, around 40% of the round timber is cut in a single cut. The remaining cross-section is rotated 60 degrees and about 60% sawn open. Finally, the remaining triangular segment of the round timber is sawn open.
- Heart plank cut, mirror cut
- A heart plank is cut from the center of the trunk. The remaining halves are divided horizontally. You get boards and planks with mostly standing growth rings.
- Quarter cut or rift
- Here a board is cut directly from the core or two boards with standing annual rings. These boards are particularly resilient, dimensionally stable and do not twist much.
- Boards of this type are of particularly high quality and are used e.g. B. used for the belt bottom (ship's bottom) or instrument making (string instruments, organ pipes).
- The term mirror cut comes from the fact that this cut hits the wood rays more or less lengthways and these appear as so-called "mirrors".
- In shipbuilding, planks cut in this way are called " wagon bulkhead cut".
- As Rift boards are with standing annual rings are not the flatter than 60 ° to the wide side of the board.
Norms and standards
Germany (and partly Austria)
- DIN 4074-1 (2003-06) Sorting wood according to load-bearing capacity - Part 1: Softwood lumber .
- DIN 4074-5 (2003-06) Sorting wood according to load-bearing capacity - Part 5: Hardwood lumber .
- is also binding for Austria as ÖNORM DIN 4074-x
- The grading classes S7 (low load-bearing capacity), S10 (red marking) and S13 (blue marking) are intended for visually sorted wood. Machine-sorted wood is labeled accordingly as C16M, C24M or C30M.
- DIN 68252-1 Terms for sawn timber, shape and dimensions .
North America (USA and Canada)
- American Softwood Lumber Standard PS-20
- NHLA Rules for the Measurement and Inspection of Hardwoods and Cypress
Economical meaning
More than half of the forest wood felled in Germany goes to the sawmill industry. The most important industries for the use of sawn timber are the construction and furniture industries. The main sales markets for the use of wood products in the construction sector (building construction) are the segments of new construction (wooden buildings), modernization (construction work on existing buildings) and the interior area (floors). In 2003, the consumption of sawn timber in building construction was approx. 13 million m³.
Word derivatives
The term board refers to a long piece of wood that is cut rather long (and along the grain).
- Window sill - today mostly made of fiber material with a melamine coating or stone, artificial stone
- Fretboard - on guitar
- Shack - a building built quickly and less permanently compared to a brick building, mainly made of wood
- Shed for boards - even faster, smaller.
- Bretterdörfer - informal settlements made of wooden houses in Vienna built from 1918 and existed until 1960.
- Wooden fence - today also made from a plastic-coated aluminum profile.
literature
- Theodor Krauth, Franz Sales Meyer (ed.): The building and art carpentry. EA Seemann, Leipzig 1895; Reprint Th. Schäfer, Hannover 1981, ISBN 3-88746-004-9 , Chapter III. The treatment and processing of wood , pp. 64–75
Web links
Individual evidence
- ↑ Definition of the term sawn timber ( Memento of the original dated December 6, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. on the website of the engineering office LGK; accessed in December 2016
- ↑ a b Fritz Spannagel: Der Möbelbau (1954): A textbook for carpenters, architects, teachers and enthusiasts , pp. 11ff and 48ff HolzWerken, 2002
- ↑ Types of incisions . In: Holzwurm-Page.de. Accessed July 2020
- ↑ Wood Lexicon , accessed on January 3, 2019.
- ↑ Roof battens on Holzfragen.de, accessed in December 2016
- ↑ American Softwood Lumber Standard PS-20. ( Memento of the original from February 27, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF) Retrieved December 23, 2013
- ↑ NHLA Rules for the Measurement and Inspection of Hardwoods and Cypress. (PDF) Retrieved December 23, 2013
- ^ Mantau, Sörgel: Wood consumption development . 2007
- ↑ Market analysis of renewable raw materials . FNR [Agency for Renewable Raw Materials], Gülzow 2006.
- ↑ Vienna's “Bretteldörfer” are explored orf.at, October 14, 2017, accessed October 14, 2017.
